A second occurrence of Yoderite

SP Johnson, Grahame John Henderson Oliver

Research output: Other contribution

Abstract

A second example of yoderite has been discovered in whiteschists from the Southern Chewore Hills of northern Zimbabwe. The mineral is pale green in colour and occurs in an equilibrium assemblage with talc + chlorite + kyanite + dravite + hematite. There is no quartz present. Recalculated microprobe analyses give a structural formula of Mg2Al5.7Fe0.3Si4O18 (OH)(2), similar to that obtained for the type locality at Mautia Hill, Tanzania, i.e. Mg2Al5.6Fe0.4Si4O18 (OH)(2). Textural relationships and relative proportions of minerals suggest that the yoderite was formed by reaction between talc, chlorite, kyanite and hematite. Experimental evidence suggests high-water-pressure metamorphic conditions at temperatures exceeding a reaction curve that extends between 13 kbar at 590 degrees C and 21 kbar at 650 degrees C. The yoderite-bearing whiteschist is associated with a 1.4 Ga dismembered ophiolite. It is proposed that this yoderite occurrence is associated with a relict subduction/suture zone.

Original languageEnglish
Volume16
Publication statusPublished - Nov 1998

Keywords

  • Chewore Hills
  • high pressure
  • natural yoderite
  • whiteschist
  • STABILITY
  • PRESSURE
  • QUARTZ

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